1. Field of the Invention
The invention relates to intracorporeal left ventricular assist devices (LVADs).
2. Prior Art
Typically, LVADs which go from the left ventricle or the left atrium to the aorta need two valves to control both inflow and outflow of blood. These valves are unidirectional valves which maintain the direction of blood flow toward the peripheral circulation, or in other desired flow directions. Examples of these types of LVADs include an LVAD which is connected through a single opening in the aorta as described by Shlomo Gabbay and which is inserted just above the aortic valve, high up in the ascending aorta. Another type of LVAD in this family was developed by Dr. John Nanas of Greece and is inserted in the abdominal aorta. Other types of LVADs take blood from the aorta and pump it back into the aorta and might better be called counterpulsating devices. The filling phase in this type of device occurs during the left ventricle systole, with blood being expelled during left ventricular diastole.
The use of two valves has generally been seen as an essential part of the LVAD which is necessary to provide unidirectional blood flow. It is also known that valves are often the most expensive element of an LVAD, and are also the most vulnerable to fail and/or serve as a site for blood clotting. Accordingly, prior art LVADs have been expensive and offer a substantial risk to the patient with respect to valve failure or other adverse conditions with respect to the blood.